If you work in a school where the proportion of pupils getting five good GCSEs is below 25 per cent, be afraid. If you are the headteacher, be very afraid. You may, like John Coughlan, of Northumberland Park community school in north London, disappear in mid-term - first mysteriously “off sick”, then unexpectedly “stepping down” - from a school where you have worked for almost three decades, without saying goodbye to staff or children.

“He was a great head and one of the reasons I joined the school,” says one teacher at Northumberland Park. “He had an open-door policy (on refugees and excluded pupils), knew his staff really well and did a lot for the children of Tottenham.”

The story of what happened to 56-year-old John Coughlan is complex, but some of those involved want to tell it, as a warning to others of what can happen when a school is put into “special measures by the back door”.

Northumberland Park serves the unfashionable east end of the borough of Haringey. When Ofsted called two years ago, the statistics told a stark story: one-third of the 1,100 students had special needs, more than half spoke English as a second language and two-thirds were entitled to free school meals. But the inspection, by Cambridge Education Associates, was positive. The school was “strongly and purposefully led by the headteacher and senior staff”, with GCSE results better than in similar schools.

Inspectors commended the commitment to inclusion and said: “Students experience respect for difference in a school that is committed to civilised values.”

Mr Coughlan, who had worked his way up to headship after starting as an English teacher almost 30 years ago, had reason to feel encouraged.

The local education authority had fared less well in its own inspection, in 1999. After a highly critical report, the then school standards minister Estelle Morris brought in a private company, Capita, to partner the authority, in an emergency rescue operation. A senior education executive from Capita, Sharon Shoesmith - a former HMI - was later appointed director of education in the troubled borough (a post she will retain when Capita’s contract ends inAugust). An inspection of the authority late last year found that it was “at least competent in almost all of its functions, although it is good in only a few”. In January, Capita put out a press release claiming among other things that the authority had “regained the trust of schools”.

Not according to the 72-signature petition sent to the governing body and Ms Shoesmith on February 11 this year by staff at Northumberland Park.

Staff complained that warning procedures had been invoked in secret against the school, in a way that damaged morale, had led to the resignation of the head - and produced no new ideas.

Haringey, as one of the five boroughs targeted by the Government’s London Challenge scheme (the others are Hackney, Islington, Lambeth and Southwark), is under particular pressure for its schools to reach the so-called “floor” target of 25 per cent of students gaining five A*-C grade GCSEs by 2006. Results at Northumberland Park, although up from 12 per cent in 1998, have hovered around the 20 per cent mark for five years. Unlike many schools, it has not introduced statistics-boosting GNVQs.

Nevertheless, the current Year 11s are predicted to break through the 25 per cent barrier, although pupil flux makes target-setting difficult; there were 222 pupils in the 2003 GCSE cohort, but more than 350 had been in the group at some time over the preceding five years.

On November 19 last year, Northumberland Park’s governing body received a formal warning under section 15 of the 1998 School Standards and Framework Act (see box). The faxed letter, from Sharon Shoesmith, identified a serious breakdown in the management of the school that was prejudicing standards. This came as a bolt from the blue to most governors.

The letter also stated that the education authority did not support Ofsted’s finding that leadership and management were strong, although the governors say they had had nothing in writing about this, nor evidence of the authority’s claim that Northumberland Park has received greater support than other schools. The formal warning also disputed the excellent value-added scores at key stage 4, which have put the school in the top 10 per cent nationally for the past two years.

In a statement to The TES, Haringey council said simply: “The school was failing to keep pace with the educational improvements taking place at similar schools in Tottenham.”

At their meeting on November 19, the governors minuted their unanimous support for the head. Documents seen by The TES show that John Coughlan then mounted a detailed rebuttal of the authority’s criticisms. He argued that while the headline GCSE figures were disappointing in 2003, other indices - such as the number of students achieving five or more A-G grades, and the decrease in the number of pupils with no passes - showed the school was making good progress.

The authority sent in a consultant headteacher, Nick Kemp (a former head of Quintin Kynaston school in Westminster), to work alongside Mr Coughlan two days a week, as well as three consultants from a private company, Education London, to carry out an “accelerated improvement review”. The consultants spent two days in the school in December before issuing its report.

Education London acknowledged that “almost all of our recommendations are built on issues and possible solutions identified by staff interviewed”, which perhaps explains the perception of the staff, voiced in their petition, that no new ideas have resulted from the overhaul.

The head and governors at Northumberland Park set about implementing the recommendations, with Mr Coughlan and Mr Kemp appearing to work harmoniously in producing a new improvement plan. Shortly afterwards, in January, Mr Coughlan went off sick. Three weeks later, at the beginning of February, the chair of governors, Reg Rice - a Labour councillor in Haringey - circulated a letter to governors announcing Mr Coughlan’s decision to take early retirement with immediate effect.

His departure remains a mystery. The letter from Mr Rice states that the head “finally decided that this was the best time for him to step down and let the school go forward”, although no explanation was given as to why the middle of the school year was a good time to resign, or what compensation was offered by the LEA. The impression at the school is that Mr Coughlan has been forced out.

“His decision to take early retirement is an unwelcome and direct result of this wholly unnecessary and poorly managed process,” said the petition from the staff.

Other heads in Haringey are concerned by the lack of transparency. Andrew Nixon, head of the high-achieving Fortismere school at the other end of the borough, is the local representative for the Secondary Heads Association.

He says: “JohnCoughlan has always been energised and on the ball in what was a very demanding community to serve. The value-added scores mean that people can only conclude that the head and staff are doing a good job. What worries me is where these decisions come from. If things are not transparent then that cannot be good for anybody and it creates anxiety, because people say, ‘Who’s next?’ ” Mr Coughlan has not spoken either to staff at the school or to the media since his decision was announced. A man described as “brilliant with children” has simply vanished. “Students are very upset,” says one teacher.

“They can’t understand why the head, who taught their parents in some cases, hasn’t said goodbye. And I can’t tell them.”

An interim head, Keith Holt, chosen by the local authority, is now in post, and the consultants from Education London will stay on to advise on the curriculum; the cost, around pound;1,000 a week, is being met by London Challenge. The section 15 notice is also about to be lifted. Haringey’s deputy director of education, Daryl Agnew, confirmed to governors before half-term that there was no obstacle to its removal.

“I’m really unhappy about what has happened,” says an LEA co-opted governor. “You would expect the LEA to have some extraordinary alternative, for us to go through this disruption, but I haven’t seen it.”

“What was the purpose of it?” asks parent governor Peter Redman, who has resigned in protest after four years’ service. “To get rid of the head.

Because nothing else has changed.” But some things are changing at Northumberland Park. “People are looking around for other posts,” says one teacher. “We all feel cheated.”

HOW SECTION 15 WORKS

Under the School Standards and Framework Act of 1998, local authorities have the power to intervene in schools that are in serious weaknesses or special measures, or where the governing body and head have already been formally warned by the LEA. A warning can be issued if the LEA believes “standards are unacceptably low and likely to remain so”, there has been a “serious breakdown in the way the school is managed” or where the safety of staff or pupils is threatened.

If the authority issues a formal warning, it recommends a course of action that must be adopted within a specified compliance period. If the head and governing body do not comply, then under section 15 of the act the LEA has the right to appoint additional governors, suspend the school’s budget or replace the governing body.

Martin Ward of the Secondary Heads Association describes the use of section 15 as “very unusual and something we would regard as somewhat sinister. It seems to enable the LEA to bypass the normal procedures, in which governors would be involved.” There is a growth, he says, of “football manager syndrome” in education. “If things are thought to be wrong with a school, there’s a marked tendency to sack the head.”